Vitamin A potentiates the mitogenic effect of epidermal growth factor in cultures of normal adult human skin fibroblasts.

The polypeptide hormone, epidermal growth factor (EGF) and Vitamin A (retinoic acid) were added to log phase cultures of adult human skin fibroblasts and the effect on cell growth observed. At the end of seven days EGF alone stimulated cell growth 68%, while trans-retinoic acid alone had no significant effect. However, when EGF was added in combination with trans-retinoic acid, cell growth was increased 159 to 214%. Cis-retinoic acid gave similar results. These results indicate that, under certain conditions, a presumed inhibitor of fibroblast growth (retinoic acid) can potentiate the mitogenic action of a hormone, namely, epidermal growth factor.